Reduction of the sulfoxide in glucoraphanin and sulforaphane by E. coli VL11 and BL21 (DE3)

• Main Authors: Vijitra Luang-In, Jaroslava Bobál’ová
• Format: Article
• Language: English
• Published: Prince of Songkla University 2016-12-01
• Series: Songklanakarin Journal of Science and Technology (SJST)
• Subjects: E. coli; glucosinolate; isothiocyanate; nitrile; sulfoxide reductase
• Online Access: http://rdo.psu.ac.th/sjstweb/journal/38-6/38-6-10.pdf

Sulfoxide reductase activity of two Escherichia coli strains VL11 from human feces and BL21(DE3) from a molecular cloning host was expressed upon glucoraphanin induction for 16 hrs at 37°C under aerobic conditions. Bacterial induced cultures were able to convert the sulfoxide in glucoraphanin to the sulfide and thus produced glucoerucin. Only E. coli VL11 produced 30 µM erucin and 51 µM erucin nitrile as degradation products from 1 mM glucoraphanin metabolism whereas BL21(DE3) only biotransformed glucoraphanin to glucoerucin with 52% conversion without metabolizing it. Cell-free extracts of each E. coli strain from glucoraphnin-induced cells in citrate phosphate buffer pH 7.0 were able to convert the sulfoxides in both glucoraphanin and sulforaphane to the sulfides and thus produced glucoerucin and erucin, respectively at 4 h under the same incubation conditions. Sulfoxide reductases from two E. coli strains required Mg2+ ions and NADPH reducing reagents for the activity.